In radio frequency (RF) transceiver systems, a duplexer or circulator is frequently used to enable simultaneous signal transmission and reception over a single antenna. A magnetic circulator routes the signals between a transmit (TX) port, an antenna port (ANT), and a receive (RX) port while providing isolation between the TX port and the RX port. The magnetic circulator includes a permanent magnet which causes signals to pass through its material along one direction, such that signals travel from the TX port to the ANT port and from the ANT port to the RX port. These magnetic circulators can be excessively large.
A traditional duplexer similarly includes an ANT port, a TX port, and an RX port, and facilitates simultaneous signal transmission and reception. With the traditional duplexer, the TX signals and RX signals are generally at different RF carrier frequencies, and the duplexer provides isolation between the TX port and RX port by filtering the signals which pass through the duplexer. The isolation between TX and RX paths of a traditional duplexer is often less than system requirements when the TX and RX carrier signals are closely spaced in the frequency domain.